Hydrocarbon drying oil



United States Patent f) HYDROCARBON DRYING OIL' George E. Serniuk,Roselle, N. .L, assignor to3Esso Research and'Engineering. Company,- acorporation of Delaware No Drawing. Application October 16, 1952,

Serial No. 315,190"

6'Claims. (Cl.260-'683.15)'

by means of solubilized Friedel-Crafts-catalysts resultsina rubberypolymer of low butadiene contentand low unsaturation. Sucha polymer isnot suitable foruse as a surface coating agent in the sense that naturaldrying oils can berused because such'pol-ymers are-notcapable of formingifirm films with the chemicaland mechanical resistances desired in asurface "coating agent. When 1Z3- butadiene and isobutylene arecopolymerized .in. aflratio.

of 40 parts'to 60 parts in ahaloalkane'diluent at about l C. using asolubilized Friedel-Crafts catalystirub ber-like, soft, light coloredpolymers of low unsaturation are obtained, thin films of Which dryveryslowly .The chemical and mechanical properties of" such films-are notsatisfactory. Under the samev conditions, polymerization of feedsconsisting of 40 to 75 parts of butadiene and 25 to 60 parts ofisobutylene results insomewhat softer polymers of intermediateunsaturation. These polymers give films which dry slowly; The water,grease, caustic and soap resistances ofsuch films are poor. Thus, byeffecting the copolymerization of'mixtures comprising varying ratios ofbutadiene and isobutylene, at varying temperatures, by means of asolubilized AlCls catalyst, resinous to rubbery or rubber-like, softpolymers are produced which are not outstanding as surface coatingagents.

It has now been found that oily-type copolymers of con.-

jugateddienes and olefins, which have excellent drying. properties, canbe prepared'by controlling the ratio of' diolefin to olefin and byemploying special catalysts. In accordance with this invention,thereactants mayoonsist of at least 75 parts of a conjugateddiolefin.and

about 25 parts of an olefin. The components to be co polymerized aredissolved in a haloalkane diluent of..l.

to 3 carbon atoms and contacted witha boron.fluoride-.

complex catalyst in the presence or absence of certain.

activators at temperatures ranging from about i3.0 Co to +100 C. underatmospheric or super-atmospheric pressure.

Suitable conjugated diene hydrocarbons include. 1,3.- butadiene, 2-methyl-1,3-butadiene, 2-chloro-li3ebutadiene,2,3-dimethyl-1,3-butadiene, 2-methyl-pentadiene;. cyclopentadiene,methylcyclopentadiene, etc.

Suitable mono-olefins. include ethylene, propylene,.land 2-butylene,isobutylene, isomeric amylenes'; cyclohexene and substitutedcyclohexenes, cyclopentene and substituted cyclopentenes, terpenes suchas c'amphene, etc.

Preferred diluents include lower alkyl halides of 1 to 3 carbon atomssuch as methyl chloride, ethyl chloride,

Butadiene ..and isobutylenemhave 2,780,664 Patented Feb. 5, 1957 2vtetrachloroethane, tetrachloroethylene, or haloalkanes containing mixedhalogens. Otherdiluents such as chlorinated aromatics, etc., mayalsobeused.

The amount of diluent required is governed, to a large extent, by thereactivity of -the diene and olefin system used. The amount of diluent,based: on the total volume of hydrocarbon reactants, may bevaried-betWeens-S to 250. volume percent-,2 preferably; 25. to: 125volume percent.

Of particularimportancein;carryingdhe present invention into. effect isthetratio of.diolefin. to olefin in: the feed.

For highly reactive drying oils the conjugated diene should Icomprise-from" 75'%"-100%' of the feed mixtureandfthe olefin "from-0''25'%'. is" preferably 'polymeriz'edbyme'ans of a specific type ofcatalyst. This catalyst is a coordination compound of a Friedel-Graftstype catalyst and an ether which may be used in conjunction with certainactivators. While any. of. the- Friedel-Craftscatalysts --such asaluminum chloride, aluminum bromide, zirconium tetrachloride, stannic.tetrachloride.v can. be. used, it 4 is particularly de-- sirable to useiboron trifiuoride since this compound when COIl'lplCXGd'Wiih-lhfi ethergives higher yieldsandv a better drying oil; Suitable .ethers includeethyl ether, b'eta,betadichloro ethylether, rnethylphenyl ether, ethyl"ph'enyl ether; andfiiphenyhether, etc. Suitable activators includeethiyl bromide, carbon tetrachloride, bromortrichloromethane;chloroform, formic acid, oxalic acid, sulfuric acid, phosphoric acid,hydrogen fluoride,- primary; .sec: ondary or. tertiary al-kylfluorides,- small amountsof ethyl alcohol or water.amounts-ranging:from: 0.1.torl0 weight percent based on thehydrocarbOnfeedz.

The amount ofcatalYst'is dependent upon the reactivity of thehydrocarbon feed and upon the temperature-ref the? reaction. Catalystconcentrations in thetorderv of 0.5 to SO'Weight percent,.based' on thehydrocarbon feed, may be used. A preferred range is 5 to 25 weight.

' plex catalyst, productsware obtained which. have superior film-formingproperties. When-cast as a filmuon': tin

plate, the-oily products :of the" present inventionshowi dryingtimes of6 to 24 hours. and remarkably high resistances to chemicals andmechanical action. However, when less of the diolefin is used, theproducts are not.suitable-asrsurface.coating agents becauseathe prod-=ucts. are. not c-apable.-of@ forming; firm films with! the, chemicaland. mechanical resistances necessary for commercial acceptance.Furthermore; becauseofthe low-- degree of unsaturation of such polymers,they react less readily with natural drying oils to form varnishes.

Theprocess according -to the present invention affords the;followingadvantages:

1. The reaction system is homogeneous.

2... An... essentially complete conversion-of thecharge- 5. The polymersPPOdiIQedl by the catalyst of thisin- I vention are oily andnon-resinous in-nature, and show approximatelyv 75% of the;- theoreticalamount of. unsaturationr 6:. After removing the diluents such..a catalystfcan be: removedi by; gravitation or.distillation-and" reused withoutany apparent loss-of activity.

The catalysts of this lllV11fi=0l1.-.(iO-JJOt-FJOSEL activity readily,can be distilled without decomposition and{can be recovered and reused.They produce polymers hav- Furthermore, the feed in this ratio Theseactivators may be used in.

EXAMPLE 1 Butadiene was copolymerized in the following manner withvarious mono-olefins:

A -liter 3-way flask fitted with a mechanical stirrer,

Dry Ice cooled reflux condenser, catalyst delivery funnel and athermometer was charged with the following:

Methyl chloride cc 770 1,3-butadiene g 750 Olefin g .250

periods of time. Generally, a total of 350 to 450 cc. of catalyst wasdelivered. The reaction temperature averaged C. After about 1 to 6 hoursthe catalyst was quenched with 100 cc. of methanol and 200 cc. ofammonium hydroxide. The quenched system was allowed to stand over nightto weather oif methyl chloride. On the following day, the oily productwas decanted from the salts. The salt was washed with naphtha andwashings combined with the main product. The salt was dissolved in aminimum amount of water and the hydrocarbon which separated wassegregated from the water layer and combined with the product. The mainproduct was treated with Attapulgus fines, allowed to stand for severalhours and then filtered. The polymer was isolated by stripping outsolvents under high vacuum.

The data are reported in the following table:

Table I.Butadiene-olefin polymers Run No Feed Composition:

Butadiene, g Isobutylene, g.

Propylene, g l-Butene, g 2-Butene, g Cyclohexene, g Diisobutyleue, g

Styrene, g Ratio Diene/Olefln Diluent:

ype Vol. used, ml. Cat. on Feed, percent..- Cat. Efiieieney 9 Reaction:

Time, 1V[in Temp., C

Recovery:

Product, g Yield, percent Product: State Fluid Fluid Very light 273.3

Light 260.8

Color Iodine No. Cg. Ii/g Percent 0 Percent H Staudinger Moi. Wt

Fluid Viscous. Viscous.

Amber.

Amber.

To the above was then added boron trifluoride-ethyl ether complex(Bakers Code 1471-Technical). A volume The product obtained from each ofthe polymerizations reported in Table I was evaluated for film dryingrate and of cc. of the catalyst corresponded to 55.6 g. The 50 chemicaland mechanical resistances thereof. The data catalyst was delivered in50 cc. increments over varying are reported in the following table:

Table lI.-Air dried and baked film properties for butadiene-olefin fluidpolymers Properties of Films Air Dried 7 and 14 Days I R Drying Rate,Hrs. aked Films un N o. Polymer H W G C F S T 1 2 4 6 24 7 14 7 14 7 147 l4 7 14 7 l4 7 14 H -W G C F S T C-lHfi/i AHB 8 7 6 5 0 4 2 0 0 0 0 82 6 6 9 0 0 0 0 0 0 0 6 0 0 C-iHs/CsHo 6 5 01 01 0 4 2 O 0 0 0 5 2 6 6 30 O 0 5 1 0 0 6 3 0 C4H /1-Butene 6-7 5 0 0 0 3 0 3 2 0 0 3 4 6 6 4 0 00 0 0 0 O 6 O 0 O4Hs/2-Buteue 6 4 0 0 0 3 2 0 0 0 0 4 3 6 6 4 2 0 0 0 00 0 6 0 O C4H6/Oyclohexane 7 4 0 0 0 8 4 0 0 0 0 3 0 0 0 0 O 6 0 0 O4H/Diis0buty1ene 9 8 7 2 0 5 2 8 0 0 3 8 5 6 6 8 5 0 O O 0 0 0 7 O 0 041106 4 1 0 0 5 1 3 1 0 0 6 2 6 5-6 3 1 0 0 5 4 0 4 6 4 0 OlHalstyrene 7 2 11 0 3 0 0 1 0 6 5 0 0 0 0 0 6 0 0 1 See Table IV for key to evaluations.2 Dione/olefin ratio-/25. I Eight day evaluations.

ease -s EXAMPLE 2 Butadiene and isobutylene were copolymerized inaccordance with Example 1 except that the diolefin/olefin Apolymerization experiment ,was made in which sulfur dioxide was used asa solventfor the reactants and as a complexing agent for the aluminumchloride catalyst. The reaction charge consisted of 75 ml. of1,3-butadiene and ml. of isobutylene and 75 ml. of sulfur dioxide. Thecharge was refrigerated externally by liquid methyl ratio was varied.The results are reported in Table III. chloride. To the charge was addedan aluminum Table III Run No A B o D Feed Composition:

Butadiene, g Isobutyleue, g.-.- Ratio diene/olefin Diluent:

Volume, ml 770 Catalyst:

Type

V01. used, ml 350 Get. on feed, percent Cat. eifieieney Reaction:

Time, Min

Temp. C Recovery:

Product, g

Yield, percent Product:

Iodine No. OgsJz/g... Staudinger M01. Wt

Liquid..

Light amber. 260.5

-.- Liquid Soft, rubbery.

Light amber Light. 238.9 359.4.

The products obtained by the above polymerization were evaluated fordrying rates and resistance to chemical and mechanical action. Theresultsare reported in Table IV and indicate the superior filmproperties of the polymer prepared from the feed of 75 parts of1,3-butadiene and 25 parts of isobutylene.

chloride-ethyl chloride catalyst containing 3.52 g. of AlCl /100 ml. ofsolution. A total of 100 ml. of the catalyst solution was added in 1-0ml. portions. The re action mixture became cloudy after a short timeafter adding the catalyst, and upon standing, a precipitate settled tothe bottom of the reactor. There was no evi- Tqble IV Properties of AirDried 7 and 14 Days Dryglg Rate, v Baked Films Run No. Polymer H W G C FS T l 2 4 6 24 7 14 7 14 7 l4 4 14 7 14 7 14 4 14 H W G O F S 'lButadieue/Isobutylene, 75/25.... 8 7 6 5 0 4 2 O 0 0 0 S 2 6 6 9 0 0 0 00 0 0 6 0 0 Butadiene/Isobutylene, 63/35---. 9 9 9 9 8 1 0 7 4 7 2 9 9 60 9 9 0 1 O 0 0 9 6 3 0 Butadiene/Isobutylenc, /45---. 9 9 9 9 8 0 3 5 24 0 9 9 0 0 -9 9 0 0 0 l 0 9 6 9 0 Butadiene 100% 6 4 1 0 0 5 1 -3 l 0 06 2 6 6 3 1 0 0 5 4 0 4 6 4 0 H=hardness; W=water resistance; G=greaseresistance; C =eaustie resistance; T=tack;

F= fiexibility; S=soap resistance.

Key to epaluation ratings Drying Rate: 9wet; 8-very sticky; 7fi1m justclings to finger; 6set to touch; 3.dccided tack but dust free; Otackfree.

Flexibility (180 bent test): O-unai'teeted; 1-4 hazed, very finecracking; 7-9 heavy cracking and saline.

Water, soap, grease and caustic resistances: 0unafl'ected; 13 discoloredor whitened and less adiic-siv'e; 4-6 softened and loss in adhesion; 7-9pinholed or blistered to failure by removal of film.

EXAMPLE 3 An apparatus similar to that described in Example 2 wascharged with the following:

1,3-butadiene g- 750 Isobutylene -g-- 250 Carbon tetrachloride -cc 50Methyl chloride --cc-- 720 dence of any polymerization reaction afteradding the above amount of catalyst. After one hour of contact, analiquot sample was removed from the reactor, and the solvents strippedtherefrom by heating on a steam plate. Upon treating the residue withwater a very small amount of polymeric material was obtained. Thereactants were allowed to contact overnight. On the following day, theamount of polymer was found to be small and about the same as was foundpreviously.

EXAMPLE 5 The data of Example 4 show that aluminum chloride at ly in thep $n of a a ge x ss o ul ur i xid was incapable of promoting anextensive copolymerization of butadiene and isobutylene. In contrast,the following data indicate that a polymer can be obtained by contactinga mixture of butadiene and isobutylene with an 7 aluminumchloride-sulfur dioxide complex catalyst in a mixed methylchloride-ethyl chloride diluent.

A. PREPARATION OF CATALYST A -liter 3-way flask, fitted with amechanical stirrer and a Dry Ice-alcohol refrigerated reflux condenser,was charged with 2400 ml. of ethyl chloride and 266.7 g. of anhydrous,sublimed aluminum chloride. To this was then added 128 g. of liquidsulfur dioxide. The mixture was stirred for one hour and then filtered.All but one gram of the aluminum chloride dissolved. Catalyst coneentration was 0.164 g. of AlClsSOz/ml. of solution.

B. POLYMERIZATION The equipment described under A was used for thepolymerization experiment. The reactor was charged with 750 g. of1,3-butadiene, 250 g. of isobutylene and 740 ml. of methyl chloride. Thetemperature of the mixture under reflux conditions was -16 C. Thecatalyst described above under A was added in 100 ml. portions over aperiod of 108 minutes. During this time, a total of 1000 ml. of catalystsolution was added. At the end of 135 minutes of contact time, thecatalyst was quenched with 100 ml. each of methyl and isopropylalcohols. The reaction mixture was diluted with 1000 ml. of naphtha.After weathering oif the low boiling solvents, the polymer solution wasseparated from the catalyst residues, treated with clay and filtered. A56 percent yield of dark amber colored product was obtained. The polymergelled when an attempt was made to remove the solvents by distillationunder vacuum.

EXAMPLE 6 A reactor as described under Example 5 was charged with 750 g.of 1,3-butadiene, 250 g. of isobutylene, 740 ml. of methyl chloride andml. of S02. To the above mixture was then delivered 1000 mls. ofaluminum chloride-ethyl chloride catalyst containing 2.48 g. of aluminumchloride/100 ml. of solution. The catalyst solution was added in 100 ml.portions over a period of 76 minutes. After a reaction period of 83minutes, the catalyst was quenched with methanol. The product wasisolated by the same procedure described under Example 5. A 14 percentyield of a dark colored resin was obtained. The polymer softening pointwas 84 C. (Ball and Ring Method) and the iodine number was 142.6 c. g.s. 12/ g. In this case, the amount of aluminum chloride usedcorresponded to 73 percent of the theoretical amount required to reactwith the sulfur dioxide.

EXAMPLE 7 Example 6 was repeated except that 1.4 times the amount ofcatalyst was used. On this basis, the aluminum chloride to sulfurdioxide mole ratio was .260/ .254. In this case, a 23 percent yield ofdark colored, resinous product was obtained. Polymer softening point was29.5 C. and the iodine number 150 c. g. s. I2/g.

EXAMPLE 8 Equipment as described in Example 5 was charged with 750 g. of1,3-butadiene, 250 g. of isobutylene, 740 ml. of methyl chloride and 5ml. of sulfur dioxide. To the above was added over a period of 49minutes, a total of 600 ml. of catalyst solution containing 3.28 'g.aluminum chloride/100 ml. of ethyl chloride solution. During theaddition of the catalyst, gel polymer was found to form within thecatalyst delivery tube which was immersed in the reactants. After 70minutes of contact time, the catalyst was quenched, and the productworked up as described under Example 5. There was obtained a 11% yieldof dark colored, resinous product. The polymer softening point was 59 C.and the iodine number 168.5 c. g. s. Iz/g. In this instance, thealuminum chloride to sulfur dioxide mole ratio was 0.147/ .127. Thus,the aluminum chloride was in excess.

. mation of polymer.

8 EXAMPLE 9 Equipment as described in Example 5 was charged with 375 g.of 1,3-butadiene, 125 g. of isobutylene and 285 ml. of methyl chloride.To the above was then added, in increments, a total of 500 ml. ofcatalyst solution comprising the complex of 74 g. of ethyl ether and 133g. of anhydrous, sublimed aluminum chloride dissolved in methyl andethyl chlorides. The concentration of aluminum chloride being 20.24 g./ml. of solution. After a reaction period of 210 minutes, the catalystwas quenched with methanol. The product was worked up by the proceduregiven under Example 5-B. A 52 percent yield of a soft, amber coloredproduct was obtained. The polymer iodine number was 232.7 c. g. s. Iz/g.

EXAMPLE 10 This example illustrates the use of a catalyst comprisinggaseous BFs dissolved in ethyl chloride for the polymerization of1,3-butadiene and isobutylene. Equipment as described in Example 5 wascharged with 375 g. of 1,3- butadiene, g. of isobutylene and 285 ml. ofmethyl chloride. To the above mixture, which showed an initialtemperature of -l5 C., was added, over a period of 178 minutes, 800 ml.of a catalyst solution consisting of gaseous BFs dissolved in ethylchloride. A total of 125 ml. of the catalyst solution required 11.2 ml.of 0.451 N caustic for titration in the cold. The temperature of thereaction mixture after adding the catalyst was 4 C. After a period of243 minutes, the catalyst was quenched with 100 ml. of equal portions ofammonium hydroxide and methanol. The low boiling solvents were allowedto Weather off. The catalyst residues were removed from the product bywater Washing. The polymer solution, after being dried, was filtered toremove gel polymer. The solvents were removed from the polymer bydistillation under vacuum. The distillation was discontinued at abottoms temperature of C. at 5 mmp. Hg. There were obtained a total of339 g. of an amber colored, viscous, fluid polymer which showed aniodine number of 210.4 0. g. s. Iz/g.

EXAMPLE 11 Equipment as described in Example 5 was charged with 375 g.of butadiene, 125 g. of isobutylene and 1000 ml. of methyl chloride.Boron trifluoride gas was delivered under the surface of. the reactionmixture in increments during a period of 26 minutes. During this time,the reaction mixture became yellow colored, viscous and foamy. Gelpolymer appeared on the walls of the reactor. At the end of 29 /2minutes, the catalyst was quenched with ammonia gas. The solution waspassed through a screen to remove gel polymer. The product was isolatedaccording to the procedure outlined in Example 10. Part of the productgelled during the solvent stripping operation. The weight of totalproduct was 159 g. or 32 percent of the total feed. The polymer wasrubbery and light colored.

EXAMPLE 12 Butadiene, 275 g., and isobutylene, 225 g., diluted with 500ml. of methyl chloride were polymerized by means of gaseous borontrifluoride admitted beneath the surface of the charge. Gel polymer wasformed and thrown out on the walls of the reactor. A 61 percent yield ofa soft, amber colored polymer was obtained which showed an iodine numberof 157.2.

EXAMPLE 13 A reactor was charged with ml. of methyl chloride, 75 ml. ofbutadiene and 25 ml. of isobutylene. To this was added a small amount ofBFs-methanol catalyst, which was prepared by adding 1 mole of BF". gasto 1 mole of anhydrous methyl alcohol refrigerated by methyl chloride. Avigorous reaction took place with the for- Upon adding additionalcatalyst the entire reaction mixture gelled.

9 EXAMPLE 14 Example 13 was repeated using less BFa-methyl alcoholcatalyst in order to avoid the formation of gel polymers By quenchingthe catalyst just short of the incipient gel point, a soluble productwas obtained which, when freed of solvents, was a resin.

The above data clearly show the remarkable superiority of the productsobtained in accordance with the present invention when the butadienecontent of the feed in the reaction charge is maintained at about 75% byweight and above. The films produced from the products obtained withlesser amounts of butadiene are still wet after air drying for 14 dayswhile the films obtained from the products made in accordance with thepresent invention are tackfree after 24 hours. Furthermore, chemicalresistances of the products prepared in accordance with the presentinvention are clearly superior.

The following conclusions are clearly evident from the above examples:

1. Products with satisfactory air-dried and baked films can be preparedby the use of the catalyst of this invention (Example 1).

2. Unsatisfactory films are obtained whenever the proportion ofbutadiene in the feed is less than 75 (Example 2).

3. Activators, such :as carbon tetrachloride, increase the yield ofpolymer (Example 3).

4. The use of an AlCla.SO2 catalyst in conjunction with a large excessof S02 resulted in an insignificant degree of polymerization (Example4).

5. An aluminum chloride-sulfur dioxide complex prepared from molarproportions of reagents formed polymer (56% yield) which gelled uponstripping the solvents. (Example 5.) Thus, such complexes give lowyields of polymer which exhibit a very low degree of thermal stability.

6. By adding aluminum chloride-ethyl chloride catalyst to a hydrocarboncharge containing varying amounts of sulfur dioxide, low yields ofresinous polymers, of a relatively low degree of unsaturation, wereproduced. (Examples 6, 7, and 8.)

7. The use of an aluminum chloride-ethyl ether catalyst resulted in alow yield of soft, viscous polymer. (Example 9.)

8. By using an ethyl chloride solution of BFa as the catalyst, a polymeryield of 68% was obtained. Example 10.) Thus by using BFs gas dissolvedin an alkyl halide, soluble polymer and some gel are produced. Anobvious disadvantage of such a system is the difliculty associated withthe recovery of the catalyst, and the formation of gel polymer.

9. By bubbling gaseous BFa into the polymerization charge, a part of thefeed forms gel polymer. This method gives low yields of polymers whichpossess a low degree of thermal stability. (Example 11.) Gelation of apart of the feed also occurred even when the butadiene-olefin ratio wasreduced to 55/45 parts. (Example 12.)

10. By using an excess of a BF -methyl alcohol catalyst the reactioncharge gelled. (Example 13.) By controlling the amount of catalystadded, soluble product was produced. This product was resinous innature. (Example 14.)

The nature of the present invention having been thus fully set forth andspecific examples of the same given, what is claimed as new and usefuland desired to be secured by Letters Patent is:

l. The process of preparing a drying oil which comprises contacting amixture of parts by weight of butadiene and 25 parts by weight ofisobutylene in the presence of about 18.6 to 25 wt. percent of a complexof boron fluoride and ethyl ether in the mole ratio of 1.0:1.0 to1.2:1.0, and in the presence of about 25 to volume percent of ahalo-alkane diluent, at a temperature of about 15 C.

2. The process of preparing a drying oil which comprises contacting amixture of 75 parts by weight of butadiene, 25 parts by weight ofisobutylene, 72 parts by weight of methyl chloride, and 8 parts byweight of carbon tetrachloride, in the presence of 44.5 parts by weightof a boron-fluoride-ethyl-ether complex at a temperature of -15 C.

3. The process of preparing a drying oil which comprises contacting amixture of 75 parts by weight of butadiene, 25 parts by weight ofisobutylene and about 77 parts by weight of methyl chloride, in thepresence of about 39 parts by weight of a boron fluoride-ethyl ethercomplex at a temperature of about 15 C.

4. A composition comprising essentially a drying oil copolymerizationproduct of a mixture of about 75% by weight butadiene and 25% by weightof a substance selected from the group consisting of hydrocarbonmonoolefins having 3 to 4 carbon atoms, said oil having an iodine numberbetween about 230 and 280 Cg.I2/g. and a Staudinger molecular weightbetween about 2000 and 4500.

5. A composition as defined by claim 4 in which monoolefin isisobutylene.

6. A composition comprising essentially a drying oil copolymerizationproduct of a mixture of about 75% by weight butadiene and about 25 byweight isobutylene, said oil having an iodine number between about 230and 260 Cg.Iz/ g. and a Staudinger molecular weight of between about2000 and 2500.

References Cited in the file of this patent UNITED STATES PATENTS2,344,213 Otto Mar. 14, 1944 2,471,890 Palmer et al. May 31, 19492,513,558 Geiser July 4, 1950 2,521,431 Walsh et al. Sept. 5, 19502,548,415 Welch et al. Apr. 10, 1951 2,569,383 Leyonmark et a1 Sept. 25,1951 2,578,214 West Dec. 11, 1951 2,588,425 Stevens et al. Mar. 11, 19522,708,639 Miller May 17, 1955 FOREIGN PATENTS 801,883 France Aug. 20,1936

1. THE PROCESS OF PREPARING A DRYING OIL WHICH COMPRISES CONTACTING AMIXTURE OF 75 PARTS BY WEIGHT OF BUTADIENE AND 25 PARTS BY WEIGHT OFISOBUTYLENE IN THE PRESENCE OF ABOUT 18.6 TO 25 WT. PERCENT OF A COMPLEXOF BORON FLUORIDE AND ETHYL ETHER IN THE MOLE RATIO OF 1.0:1.0 TO1.2:1.0, AND IN THE PRESENCE OF ABOUT 25 TO 125 VOLUME PRECENT OF AHALO-ALKANE DILUENT, AT A TEMPERATURE OF ABOUT -15*C.